ANSC 260

  1. Feed intake regulation
    The interrelated mechanisms that attempt to regulate energy intake, in relation to energy expenditures
  2. Hunger
    The complex of sensations which compels an animal to obtain food
  3. Satiety
    The complex of sensations which compels an animal to stop eating
  4. Palatability
    The degree of readiness with which a particular feed is selected and eaten
  5. Factors affecting feed intake
    • Species: breed
    • Sex: extrus
    • Environment: space, stocking density, nutritional factors, physiological state
    • Palatibility
    • Age
  6. Palatability affected by
    • Taste (bitter, sour, salty, sweet, umami, kokumi)
    • -tastebuds, greatest to least: chicken, dog, human, sheep & goat, cattle
    • odour
    • sight (orientation and texture)
    • texture (particle size)
    • novelty
  7. Summary feed intake
    • Generally, animals eat to meet their energy requirements
    • Changing circumstances energy output increases, energy input changes
  8. Short-term control of feed intake (hours)
    • Neural receptors and afferent neutrons
    • -GI tract, liver, other organs
    • Gastric distencion/contraction
    • Humoral factors - hormones & metabolites
    • Glucostatic theory (intake controled by blood glucose)
    • Aminostatic control
    • -monogastrics crave specific amino acids
    • Thermostatic control
  9. Long-term control of feed intake
    • Animals seldom starve or overeat
    • Hibernating animals
    • Combination of signals that contribute to long-term control of feed intake
  10. Lipostatic control
    Animals eat to maintain set lipid reserves
  11. Seasonal affects
    Regulated in part by the pineal gland
  12. Current understanding
    • Multiple control mechanisms working together
    • CNS recieves, integrates information
  13. Gastrointestinal receptors
    • Chemical:
    • -receptor in gut for fat & protein
    • -receptors for blood glucose
    • Osmotic pressure
    • Stretch receptors
  14. Hormone controls
    • Cholecystokinin
    • -released in resonse to fat & protein in the small intestine
    • -hunger suppressant
    • Insulin
    • -reduces food intake-anorexia
    • -uptake of glucose by cells
    • -reduced insulin sensitivity ->obesity and diabetics
    • Leptin
    • -most important hormone regulating energy balance
    • -feedback regulation
    • Ghrelin
    • -increases foo intake
    • -released by the stomache
    • -counterpart to leptin
  15. Physiological responses that affect feed intake
    • Growth hormone
    • Stress hormone
    • Reproductive hormone
    • Opioids
    • Immune hormone
  16. CNS control of feed intake
    • Control of feed intake is ultimately under the control of the brain.
    • Hypothalamus
    • Ventromedial nucleus (satiety centre)
    • Lateral nucleus (hunger centre)
  17. In most production situations
    • High feed intake is necessary
    • Efficiency of production generally realtes to energy intake
  18. FCR
    • Feed Conversion Rate
    • g feed/g gain
  19. Residual feed intake
    • Acurate feed intake - expected feed intake
    • Expected feed intake is based on calculated requirements
  20. Restrict feed intake:
    Broiler breeders, sows, compensatory growth
Card Set
ANSC 260
After midterm